Thermal insulation used in insulating buildings, particularly residential buildings, has heretofore been predominantly fiberglass. Such fiberglass insulation typically is used in both loose or blown form and in batts with and without a layer of paper or vinyl on one side. Because of certain concerns about fiberglass, there has developed a need for economically feasible alternatives to fiberglass insulation.
Examples of prior attempts to meet this need are disclosed in U.S. Pat. No. 4,678,822 to Lewellin and U.S. Pat. No. 5,057,168 to Muncrief. Lewellin describes a method of forming a bonded fiber insulation batt in which cotton fibers are bonded together by a RHOPLEX resin emulsion. While certainly a step in the right direction, Lewellin's batt was more dense than was desirable and the weight thereof was excessive.
Muncrief disclosed a low density, mainly cotton insulation bonded into batt form by polyester fibers mixed with the insulation fibers and heated to their softening temperature. Muncrief also discloses the addition of stilt fibers, in the form of gin motes and linters, short acrylic fibers or the like, and these stilt fibers are either mixed with the insulative fibers or spread between the layers of insulative fibers forming the batt. In addition, Muncrief discloses the addition of powdered, dry fire retardant chemicals to his insulation material in an attempt to provide the requisite fire retardancy. Such dry fire retardant chemicals have been found to be less than desirable to provide a high degree of fire retardancy.
While certainly an improvement over fiberglass insulation and the resin-bonded insulation of Lewellin, the process of Muncrief was still less than desirable from manufacturing and cost standpoints and from a product quality standpoint. Muncrief's process was somewhat labor intensive and lacked other processing features which would reduce the incremental cost of producing such insulation.